Treatment of hyperuricemia in humans

ABSTRACT

The method of treatment and prophylaxis for hyperuricemia, which comprises administering to a human patient a therapeutically effective amount of a compound selected from the class consisting of 4-hydroxy-1-H-pyrazolo(3,4-d)pyrimidine and 4,6-dihydroxy-1-Hpyrazolo(3,4-d)pyrimidine.

United States Patent Inventors Appl. No.

Priorities George H. Hitchlngs Yonkers;

Elvira A. Falco, New Rochelle, both of N.Y. 633,364

Apr. 25, 1967 Nov. 30, 197 1 Burroughs Wellcome 8: Co. (U.S.A.) lnc. Tuckahoe, NY.

Aug. 10, 1955 Great Britain May 23, 1962, Great Britain, No. 19,863/62; Aug. 23, 1962, Great Britain, No. 34,519/62 Continuation-impart of application Ser. No.

574,576, Mar. 29, 1956, now abandoned Continuation-impart of application Ser. No.

22,394, Apr. 15, 1960, now abandoned Continuation-impart of application Ser. No.

221,357, Sept. 4, 1962, now abandoned Continuation-impart of application Ser. No.

524,873, Feb. 3, 1966, now abandoned. This application Apr. 25, 1967, Ser. No. 633,364

Elion et al., Cancer Chemotherapy Reports, No. 16, Feb. 1962, pages I97- 202 (copy in P.O.S.L.)

Primary Examiner-Jerome D. Goldberg Attorney-Dike, Thompson & Bronstein ABSTRACT: The method of treatment and prophylaxis for hyperuricemia, which comprises administering to a human patient a therapeutically effective amount of a compound selected from the class consisting of 4-hydroxy-l-H- pyrazolo( 3,4-d )pyrimidine and 4,6-dihydroxyl -H- pyrazolo(3,4-d)pyrimidine.

TREATMENT OF HYPERURICEMIA IN HUMANS This is a continuation in part of our applications Ser. No. 574,576 filed Mar. 29, 1956, now abandoned; Ser. No. 22,394 filed Apr. 15, 1960, now abandoned; Ser. No. 221,357 filed Sept. 4, l962, now abandoned; and -Ser. No. 524,873 filed Feb. 3, 1966, now abandoned.

This invention relates to a method of treatment and prophlaxis for hyperuricemia in mammals such as human patients.

It has been found that certain new pyrazolo(3,4- d)pyrimidines, by reason of their close resemblance in structure to the substrates for the enzyme xanthine oxidase, hypoxanthine (6-hydroxypurine) and xanthine (2,6-dihydroxypurine are capable of binding to this enzyme and strongly inhibiting its activity.

The compounds of the present invention comprise pyrazolo( 3,4-d)pyrimidines of the general formula:

wherein X is hydroxyl and Y is hydroxyl and, further, may be as hydrogen.

A very valuable property of these derivatives and, particularly, 4-hydroxy-l-H-pyrazolo(3,4-d(pyrimidine (HPP) and 4,6-dihydroxyl -l-l-pyrazolo(3,4-d(pyrimidine (DHPP), is the inhibition of the systemic enzyme xanthine oxidase in vivo.

Hyperuricemias, both primary and secondary, are associated with gout and uric acid lithiasis of the kidney and related complications. Hyperuricemia may also be iatrogenic in origin, secondary to the use of thiazide diuretics, or drugs such as 2-ethylaminol ,3,4-thiadiazole.

It is apparent, therefore, that an inhibition of xanthine oxidase activity in vivo is useful in reducing the metabolic production of uric acid, thereby providing a method of treating hyperuricemia.

Many patients afflicted with gout (which is a form of hyperuricemia) form and secrete abnormally large amounts of uric acid crystals in the joints. Such patients often develop kidney stones composed of uric acid which cause pain and renal damage. The use of the xanthine oxidase inhibitors disclosed here can prevent the formation of such excessive amounts of uric acid.

For use in the treatment of hyperuricemia, gout being one form thereof, the xanthine oxidase inhibitor mentioned above may be conveniently presented as a combined pharmaceutical formulation, the uricosuric drugs now utilized in treating patients having excess uric acid.

The compounds may thus advantageously be presented in discreet units such as tablets, capsules, cachets, ampuls or suppositories, each containing a predetermined amount of xanthine oxidase inhibitor. The active ingredients may also be presented in a powder or granules, as a solution or suspension in an aqueous, nonaqueous or emulsified liquid. For parenteral use, the formulations must be sterile and are presented in sealed containers. The formulations of this invention may be made by any of the methods of pharmacy and may include one or more of the following accessory ingredients: diluents, solutes, buffers, flavoring, binding, dispersing, surface-active, thickening, lubricating and coating materials, preservatives, antioxidants, bacteriostats, suppository and ointment bases, and any other acceptable excipients. A preferred form is a compressed tablet containing 100 mg. of the active ingredient with about 350 mg. of lactose and suitable granulating and lubricating materials.

As may be seen from table 2 above, daily dosage of 4- hydroxypyrazolo(3,4-d)pyrimidine is ordinarily in the range of 100 mg. to 800 mg. per dosage, range for the disubstituted compounds is ordinarily somewhat higher. In some instances a loading dose about twice the daily dose is desirable.

The present invention, therefore, comprises the treatment and prophylaxis for hyperuricemia by the administration of a compound selected from the class consisting of 4-hydroxypyrazolo( ISA-d)pyrimidine and 4,6-dihydroxypyrazolo( 3 ,4d- (pyrimidine to a human patient or other mammal. The dosage administered is preferably 2 to 30 mg./kg. of body weight per day.

The invention will now be described with reference to the following examples, in which all temperatures are given in degrees Centigrade.

EXAMPLE I Pyrazolo3,4-dicarboxamide To 7.5 g. of pyrazolo-3,4-dicarboxylic acid there was added 150 ml. of thionyl chloride. This mixture was heated under reflux conditions for 10 hours. The thionyl chloride was removed in vacuo and the powdery residue was added, in portions, to a cold, stirred solution of tertbutanol which had been saturated with amonia at 0. After the compound had all been added (1 hour), the mixture was allowed to stand for an additional 5 hours. The precipitate was then removed and boiled with ml. of concentrated ammonium hydroxide solution 1 hour). This solution was allowed to evaporate to dryness on the steam bath and the residue crystallized from boiling water.

The compound thus obtained formed colorless plates melting with decomposition at 327.

EXAMPLE 2 4,6-Dihydroxy- 1 -pyrazolo( 3,4-d )pyrimidine To a cold solution of 16.6 ml. of 0.4 M sodium hypochlorite solution was added (all at once) 500 mg. of pyrazole-3,4- dicarboxamide. The reaction mixture turned pink and then faintly yellow. After standing at 0' for 1 hour, the reaction mixture was acidified to pH with 2-N hydrochloric acid, and the flocculent precipitate was removed. The compound was recrystallized from boiling water to give colorless needles, in rosettes. The compound does not melt at 320.

EXAMPLE 3 Preparation of 4-mercapto-6-hydroxyl -pyrazolo( 3 ,4- d )pyrimidine To 4 g. of the 4,6-dihydroxy compound described in example 2, there was added 12 g. of phosphorus pentasulfide and 60 ml. of dry pyridine. This mixture was heated for 3 hours at reflux temperature. The pyridine was removed in vacuo and the residue taken up in cold dilute sodium hydroxide solution. On acidification, there was obtained 3.5 g. of a pale yellow compound. This compound, after crystallization from boiling water, formed yellow plates which do not melt at 360". This compound had the following u.v. absorption spectrum: at pH 1 the maxima are at 255 and 330 My, while at pH ll the peaks are at 255 and 330 Ma.

EXAMPLE 4 Preparation of the 4,6-dimercaptol -pyrazolo( 3,4- d)pyrimidine To the monomercapto compound described in example 3 l g.) there was added 3 g. of phosphorus pentasulfide and 60 ml. of pyridine. This mixture was heated for 16 hours and worked up as described in example 3. The compound was crystallized from boiling water to give a yellow powder which did not decompose at 320.

EXAMPLE 5 Preparation of 4-amino-6-mercaptol -pyrazolo-( 3,4-d pyrimidine To 650 mg. of 4,6-dimercapto-l-pyrazolo(3,4-d)pyrimidine there was added 200 ml. of alcohol (saturated with ammonia at This mixture was heated in a sealed tube at 149 for 18 hours. The bomb contents were then allowed to evaporate to dryness on the steam bath. The residue was taken up in cold EXAMPLE 6 Preparation of 4-amino-l-pyrazolo3,4-d)pyrimidine To 1.0 g. of the above 4-amino-6-mercaptol pyrazolo( 3,4- d)pyrimidine there was added ml. of concentrated ammonium hydroxide solution, 200 ml. of water and 5 g. of Raney nickel catalyst. The mixture was heated at reflux temperature for 3 hours and the solution filtered hot from the Raney nickel. The residual Raney nickel was extracted twice with 100 ml. portions of hot water and filtered. The combined filtrates were concentrated to dryness in vacuo and taken up in 200 ml. of hot ethanol. To the ethanol was added 10 ml. of 33 percent alcoholic hydrochloric acid and 500 ml. of ether. On standing for 24 hours, rosettes of colorless needles precipitated. These needles were recrystallized from 95 percent ethanol to give 4-aminol-pyrazolo(3,4-d)pyrimidine hydrochloride.

EXAMPLE 7 Preparation of 4-hydroxyl -pyrazolo( 3,4-d )pyrimidine One gram of the above amino compound was placed in 100 ml. of 0.2N sulfuric acid and warmed on the steam bath. To this was added a solution of 1.7 g. of potassium nitrite in 5 ml. of water. The mixture was then boiled for five minutes. The reaction mixture was cooled, brought to pH 5.5 by the addition of ammonium hydroxide solution and concentrated in vacuo to a volume of 20 ml. on standing in the cold for several hours, a precipitate formed which was recrystallized from boiling water to give a colorless powder which did not melt at 320. This compound is 4-hydroxy-l-pyrazolo(3,4- d)pyrimidine What is claimed is:

1. The method of treatment and prophylaxis for hyperuricemia, which comprises administering to a human patient a therapeutically effective amount of a compound 4-hydroxyl H-pyrazolo( 3 ,4-d )pyrimidine.

2. The method of claim 1, wherein the compound 4-hydroxyl-H-pyrazolo(3,4-d)pyrimidinc. is administered at a dosage of 2 to 30 mg./kg. of the body weight of the human patient treated.

3. The method of treatment and prophylaxis for hyperuricemia, which comprises administering to a human patient a therapeutically effective amount of a compound 4,6-dihydroxy-1-H-pyrazolo(3,4-d)pyrimidine.

4. The method claim 3, wherein the compound 4,6- dihydroxy-l-H-pyrazolo(3,4-d)pyrimidine is administered at a dosage of 2 to 30 mg./kg. of the body weight of the human patient treated.

5. The method of treatment and prophylaxis for hyperuricemia, which comprises administering to a human patient a therapeutically effective amount of a compound selected from the class consisting of 4-hydroxy-l-H-pyrazolo(3,4- d )pyrimidine and 4,6-dihydroxy- I -H-pyrazolo-( 3 ,4- d)pyrimidine.

UNITED STATES PATENT AND TRADEMARK OFFICE Certificate Patent No. 3,624,205 Patented June 30, 1971 George H. Hitchings & Elvira A. Falco Application having been made by George H. Hitchings and Elvira A. Falco, the inventors named in the patent above identified, and Burroughs Wellcome Co., a corp. of NC, the assignee, for the issuance of a certificate under the provisions of Title 35, Section 256, of the United States Code, deleting the name of Elvira A. Falco as a joint inventor, and a showing and proof of facts satisfying the requirements of the said section having been submitted, it is this 27th day of October 1981, certified that the name of the said Elvira A. Falco is hereby deleted from the said patent as a joint inventor with the said George H. Hitchings.

Fred W. Sherling Associate Solicitor. 

2. The method of claim 1, wherein the compound 4-hydroxy-1-H-pyrazolo(3,4-d)pyrimidine is administered at a dosage of 2 to 30 mg./kg. of the body weight of the human patient treated.
 3. The method of treatment and prophylaxis for hyperuricemia, which comprises administering to a human patient a therapeutically effective amount of a compound 4,6-dihydroxy-1-H-pyrazolo(3,4-d)pyrimidine.
 4. The method claim 3, wherein the compound 4,6-dihydroxy-1-H-pyrazolo(3,4-d)pyrimidine is administered at a dosage of 2 to 30 mg./kg. of the body weight of the human patient treated.
 5. The method of treatment and prophylaxis for hyperuricemia, which comprises administering to a human patient a therapeutically effective amount of a compound selected from the class consisting of 4-hydroxy-1-H-pyrazolo(3,4-d)pyrimidine and 4,6-dihydroxy-1-H-pyrazolo-(3,4-d)pyrimidine. 